/*
 * Westwood Studios VQA Format Demuxer
 * Copyright (c) 2003 Mike Melanson <melanson@pcisys.net>
 * Copyright (c) 2021 Pekka Väänänen <pekka.vaananen@iki.fi>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * Westwood Studios VQA file demuxer
 * by Mike Melanson (melanson@pcisys.net)
 * for more information on the Westwood file formats, visit:
 *   http://www.pcisys.net/~melanson/codecs/
 *   http://www.geocities.com/SiliconValley/8682/aud3.txt
 */

#include "libavutil/intreadwrite.h"
#include "avformat.h"
#include "avio_internal.h"
#include "demux.h"
#include "internal.h"

#define FORM_TAG MKBETAG('F', 'O', 'R', 'M')
#define WVQA_TAG MKBETAG('W', 'V', 'Q', 'A')
#define VQHD_TAG MKBETAG('V', 'Q', 'H', 'D')
#define FINF_TAG MKBETAG('F', 'I', 'N', 'F')
#define SND0_TAG MKBETAG('S', 'N', 'D', '0')
#define SND1_TAG MKBETAG('S', 'N', 'D', '1')
#define SND2_TAG MKBETAG('S', 'N', 'D', '2')
#define VQFR_TAG MKBETAG('V', 'Q', 'F', 'R')
#define VQFL_TAG MKBETAG('V', 'Q', 'F', 'L')

/* don't know what these tags are for, but acknowledge their existence */
#define CINF_TAG MKBETAG('C', 'I', 'N', 'F')
#define CINH_TAG MKBETAG('C', 'I', 'N', 'H')
#define CIND_TAG MKBETAG('C', 'I', 'N', 'D')
#define LINF_TAG MKBETAG('L', 'I', 'N', 'F')
#define PINF_TAG MKBETAG('P', 'I', 'N', 'F')
#define PINH_TAG MKBETAG('P', 'I', 'N', 'H')
#define PIND_TAG MKBETAG('P', 'I', 'N', 'D')
#define CMDS_TAG MKBETAG('C', 'M', 'D', 'S')
#define SN2J_TAG MKBETAG('S', 'N', '2', 'J')
#define VIEW_TAG MKBETAG('V', 'I', 'E', 'W')
#define ZBUF_TAG MKBETAG('Z', 'B', 'U', 'F')

#define VQA_HEADER_SIZE 0x2A
#define VQA_PREAMBLE_SIZE 8

typedef struct WsVqaDemuxContext {
    int version;
    int bps;
    int channels;
    int sample_rate;
    int audio_stream_index;
    int video_stream_index;
    int64_t vqfl_chunk_pos;
    int vqfl_chunk_size;
} WsVqaDemuxContext;

static int wsvqa_probe(const AVProbeData *p)
{
    /* need 12 bytes to qualify */
    if (p->buf_size < 12)
        return 0;

    /* check for the VQA signatures */
    if ((AV_RB32(&p->buf[0]) != FORM_TAG) ||
        (AV_RB32(&p->buf[8]) != WVQA_TAG))
        return 0;

    return AVPROBE_SCORE_MAX;
}

static int wsvqa_read_header(AVFormatContext *s)
{
    WsVqaDemuxContext *wsvqa = s->priv_data;
    AVIOContext *pb = s->pb;
    AVStream *st;
    uint8_t *header;
    uint8_t scratch[VQA_PREAMBLE_SIZE];
    uint32_t chunk_tag;
    uint32_t chunk_size;
    int fps, ret;

    /* initialize the video decoder stream */
    st = avformat_new_stream(s, NULL);
    if (!st)
        return AVERROR(ENOMEM);
    st->start_time = 0;
    wsvqa->video_stream_index = st->index;
    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
    st->codecpar->codec_id = AV_CODEC_ID_WS_VQA;
    st->codecpar->codec_tag = 0;  /* no fourcc */

    /* skip to the start of the VQA header */
    avio_seek(pb, 20, SEEK_SET);

    /* the VQA header needs to go to the decoder */
    if ((ret = ff_get_extradata(s, st->codecpar, pb, VQA_HEADER_SIZE)) < 0)
        return ret;
    header = st->codecpar->extradata;
    st->codecpar->width = AV_RL16(&header[6]);
    st->codecpar->height = AV_RL16(&header[8]);
    fps = header[12];
    st->nb_frames =
    st->duration  = AV_RL16(&header[4]);
    if (fps < 1 || fps > 30) {
        av_log(s, AV_LOG_ERROR, "invalid fps: %d\n", fps);
        return AVERROR_INVALIDDATA;
    }
    avpriv_set_pts_info(st, 64, 1, fps);

    wsvqa->version      = AV_RL16(&header[ 0]);
    wsvqa->sample_rate  = AV_RL16(&header[24]);
    wsvqa->channels     = header[26];
    wsvqa->bps          = header[27];
    wsvqa->audio_stream_index = -1;
    wsvqa->vqfl_chunk_pos     = 0;
    wsvqa->vqfl_chunk_size    = 0;

    s->ctx_flags |= AVFMTCTX_NOHEADER;

    /* there are 0 or more chunks before the FINF chunk; iterate until
     * FINF has been skipped and the file will be ready to be demuxed */
    do {
        if (avio_read(pb, scratch, VQA_PREAMBLE_SIZE) != VQA_PREAMBLE_SIZE)
            return AVERROR(EIO);
        chunk_tag = AV_RB32(&scratch[0]);
        chunk_size = AV_RB32(&scratch[4]);

        /* catch any unknown header tags, for curiosity */
        switch (chunk_tag) {
        case CINF_TAG:
        case CINH_TAG:
        case CIND_TAG:
        case LINF_TAG:
        case PINF_TAG:
        case PINH_TAG:
        case PIND_TAG:
        case FINF_TAG:
        case CMDS_TAG:
        case VIEW_TAG:
        case ZBUF_TAG:
            break;

        default:
            av_log(s, AV_LOG_ERROR, " note: unknown chunk seen (%s)\n",
                   av_fourcc2str(chunk_tag));
            break;
        }

        avio_skip(pb, chunk_size);
    } while (chunk_tag != FINF_TAG);

    return 0;
}

static int wsvqa_read_packet(AVFormatContext *s,
                             AVPacket *pkt)
{
    WsVqaDemuxContext *wsvqa = s->priv_data;
    AVIOContext *pb = s->pb;
    int ret = -1;
    uint8_t preamble[VQA_PREAMBLE_SIZE];
    uint32_t chunk_type;
    uint32_t chunk_size;
    int skip_byte;

    while (avio_read(pb, preamble, VQA_PREAMBLE_SIZE) == VQA_PREAMBLE_SIZE) {
        chunk_type = AV_RB32(&preamble[0]);
        chunk_size = AV_RB32(&preamble[4]);

        skip_byte = chunk_size & 0x01;

        if (chunk_type == VQFL_TAG) {
            /* Each VQFL chunk carries only a codebook update inside which must be applied
             * before the next VQFR is rendered. That's why we stash the VQFL offset here
             * so it can be combined with the next VQFR packet. This way each packet
             * includes a whole frame as expected. */
            wsvqa->vqfl_chunk_pos = avio_tell(pb);
            wsvqa->vqfl_chunk_size = (int)(chunk_size);
            if (wsvqa->vqfl_chunk_size < 0 || wsvqa->vqfl_chunk_size > 3 * (1 << 20))
                return AVERROR_INVALIDDATA;
            /* We need a big seekback buffer because there can be SNxx, VIEW and ZBUF
             * chunks (<512 KiB total) in the stream before we read VQFR (<256 KiB) and
             * seek back here. */
            ffio_ensure_seekback(pb, wsvqa->vqfl_chunk_size + (512 + 256) * 1024);
            avio_skip(pb, chunk_size + skip_byte);
            continue;
        } else if ((chunk_type == SND0_TAG) || (chunk_type == SND1_TAG) ||
            (chunk_type == SND2_TAG) || (chunk_type == VQFR_TAG)) {

            ret= av_get_packet(pb, pkt, chunk_size);
            if (ret<0)
                return AVERROR(EIO);

            switch (chunk_type) {
            case SND0_TAG:
            case SND1_TAG:
            case SND2_TAG:
                if (wsvqa->audio_stream_index == -1) {
                    AVStream *st = avformat_new_stream(s, NULL);
                    if (!st)
                        return AVERROR(ENOMEM);

                    wsvqa->audio_stream_index = st->index;
                    if (!wsvqa->sample_rate)
                        wsvqa->sample_rate = 22050;
                    if (!wsvqa->channels)
                        wsvqa->channels = 1;
                    if (!wsvqa->bps)
                        wsvqa->bps = 8;
                    st->codecpar->sample_rate = wsvqa->sample_rate;
                    st->codecpar->bits_per_coded_sample = wsvqa->bps;
                    av_channel_layout_default(&st->codecpar->ch_layout, wsvqa->channels);
                    st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;

                    avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);

                    switch (chunk_type) {
                    case SND0_TAG:
                        if (wsvqa->bps == 16)
                            st->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE;
                        else
                            st->codecpar->codec_id = AV_CODEC_ID_PCM_U8;
                        break;
                    case SND1_TAG:
                        st->codecpar->codec_id = AV_CODEC_ID_WESTWOOD_SND1;
                        break;
                    case SND2_TAG:
                        st->codecpar->codec_id = AV_CODEC_ID_ADPCM_IMA_WS;
                        if ((ret = ff_alloc_extradata(st->codecpar, 2)) < 0)
                            return ret;
                        AV_WL16(st->codecpar->extradata, wsvqa->version);
                        break;
                    }
                }

                pkt->stream_index = wsvqa->audio_stream_index;
                switch (chunk_type) {
                case SND1_TAG:
                    /* unpacked size is stored in header */
                    if(pkt->data)
                        pkt->duration = AV_RL16(pkt->data) / wsvqa->channels;
                    break;
                case SND2_TAG:
                    /* 2 samples/byte, 1 or 2 samples per frame depending on stereo */
                    pkt->duration = (chunk_size * 2) / wsvqa->channels;
                    break;
                }
                break;
            case VQFR_TAG:
                /* if a new codebook is available inside an earlier a VQFL chunk then
                 * append it to 'pkt' */
                if (wsvqa->vqfl_chunk_size > 0) {
                    int64_t current_pos = pkt->pos;

                    if (avio_seek(pb, wsvqa->vqfl_chunk_pos, SEEK_SET) < 0)
                        return AVERROR(EIO);

                    /* the decoder expects chunks to be 16-bit aligned */
                    if (wsvqa->vqfl_chunk_size % 2 == 1)
                        wsvqa->vqfl_chunk_size++;

                    if (av_append_packet(pb, pkt, wsvqa->vqfl_chunk_size) < 0)
                        return AVERROR(EIO);

                    if (avio_seek(pb, current_pos, SEEK_SET) < 0)
                        return AVERROR(EIO);

                    wsvqa->vqfl_chunk_pos = 0;
                    wsvqa->vqfl_chunk_size = 0;
                }

                pkt->stream_index = wsvqa->video_stream_index;
                pkt->duration = 1;
                break;
            }

            /* stay on 16-bit alignment */
            if (skip_byte)
                avio_skip(pb, 1);

            return ret;
        } else {
            switch(chunk_type){
            case CMDS_TAG:
            case SN2J_TAG:
            case VIEW_TAG:
            case ZBUF_TAG:
                break;
            default:
                av_log(s, AV_LOG_INFO, "Skipping unknown chunk %s\n",
                       av_fourcc2str(av_bswap32(chunk_type)));
            }
            avio_skip(pb, chunk_size + skip_byte);
        }
    }

    return ret;
}

const AVInputFormat ff_wsvqa_demuxer = {
    .name           = "wsvqa",
    .long_name      = NULL_IF_CONFIG_SMALL("Westwood Studios VQA"),
    .priv_data_size = sizeof(WsVqaDemuxContext),
    .read_probe     = wsvqa_probe,
    .read_header    = wsvqa_read_header,
    .read_packet    = wsvqa_read_packet,
};